To be able to ssh to CS machines without giving your password each time, give these commands from macOS. Note that CS.STANFORD.EDU must be all uppercase. Replace "xenon" with the name of the host you want to ssh to.
> kinit yourCSID@CS.STANFORD.EDU
> ssh -o GSSAPIDelegateCredentials=yes -o GSSAPIAuthentication=yes xenon.stanford.edu
(You don't need to have AFS installed on your Mac for password-less SSH to work.)
To make the GSSAPI options above default to 'yes', you can add the following to your
Host *.stanford.edu GSSAPIDelegateCredentials yes GSSAPIAuthentication yes
Some additional info here: http://snap.stanford.edu/moin/SshKerberosMac, but don't install the KCT app mentioned on the page.